*2.7. UV-vis Transmittance of Films*

Figure 10a presents the images of as prepared pure ALG/G film as well as of ALG/G/ xNZ and ALG/G/xTO@NZ nanocomposite films. Figure 8b presents the UV-vis transmittance plots of all obtained films. It is obvious from both images and UV-vis plots that the TO@NZ based films are more transparent than NZ based counterparts. Higher transparency indicates higher nanofiller dispersion and integration inside the polymer matrix. Thus, it seems that the TO enhances the dispersion of the NZ in ALG/G/xTO@NZ nanocomposite films. Moreover, the lowest transparency is obtained for ALG/G/15NZ and ALG/G/15TO@NZ films.

**Figure 10.** (**a**) photo images of all prepared films, (**b**) UV-vis transmittance of all prepared films. (1) pure ALG/G, (2) ALG/G/5NZ, (3) ALG/G/10NZ, (4) ALG/G/15NZ, (5) ALG/G/5TO@NZ, (6) ALG/G/10TO@NZ and (7) ALG/G/15TO@NZ films. **Figure 10.** (**a**) photo images of all prepared films, (**b**) UV-vis transmittance of all prepared films.(1) pure ALG/G, (2) ALG/G/5NZ, (3) ALG/G/10NZ, (4) ALG/G/15NZ, (5) ALG/G/5TO@NZ, (6) ALG/G/10TO@NZ and (7) ALG/G/15TO@NZ films.

**Table 1.** Calculated values of Young's (E) Modulus, ultimate tensile strength (σuts) and % strain at

ALG/G 445.5 (63.8) 15.2 (2.4) 40.2 (4.7) ALG/G/5NZ 755.6 (67.3) 22.7 (0.9) 24.7 (12.4) ALG/G/10NZ 669.3 (24.3) 21.1 (5.9) 20.3 (2.7) ALG/G/15NZ 785.3 (146.6) 23.1 (5.5) 23.1 (2.5) ALG/G/5TO@NZ 739.4 (20.3) 20.9 (3.5) 28.4 (8.2) ALG/G/10TO@ΝΖ 651.5 (76.2) 18.5 (2.9) 28.3 (6.6) ALG/G/15TO@NZ 798.5 (177.5) 22.6 (1.4) 25.3 (2.5)

It is obvious from Table 1 that the addition of both NZ and TO@NZ hybrid nanostructure increases stiffness and strength and decreases %elongation at break values. The nanocomposite film with the higher strength was the ALG/G/15NZ and ALG/G/15TO@NZ. This result is in accordance with previous reports where zeolite was successfully incorporated into polyethylene/caprolactone [28], cellulose [29,44], and chitosan [30] films as nano-reinforcement. The result also agrees with the FTIR morphological evaluation of such films where an interplay between NZ, TO@NZ hybrid nanostructures and ALG/G matrix was obtained. In general, ALG/G/TO@NZ based nanocomposite films exhibited higher elongation at break values than the ALG/G/NZ due to the presence of TO mole-

Figure 10a presents the images of as prepared pure ALG/G film as well as of ALG/G/xNZ and ALG/G/xTO@NZ nanocomposite films. Figure 8b presents the UV-vis transmittance plots of all obtained films. It is obvious from both images and UV-vis plots that the TO@NZ based films are more transparent than NZ based counterparts. Higher transparency indicates higher nanofiller dispersion and integration inside the polymer matrix. Thus, it seems that the TO enhances the dispersion of the NZ in ALG/G/xTO@NZ nanocomposite films. Moreover, the lowest transparency is obtained for ALG/G/15NZ

**(MPa) σuts (MPa) %<sup>ε</sup>**

**Code Name E-Elastic Modulus** 

#### *2.8. Water-Oxygen Barrier Properties 2.8. Water-Oxygen Barrier Properties*

cules which acted as plasticizers [22,45].

*2.7. UV-vis Transmittance of Films* 

and ALG/G/15TO@NZ films.

break (εb).

Water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) values for all ALG/G/xNZ and ALG/G/xTO@NZ films are listed in Table 2. Using these values, Water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) values for all ALG/G/xNZ and ALG/G/xTO@NZ films are listed in Table 2. Using these values, water vapor diffusivity (DWV) and oxygen permeability (PeO2) values were calculated and listed in the same table.

**Table 2.** Measured values of water-vapor transmission rate WVTR and oxygen transmission rate OTR. Calculated values of water diffusion coefficient DWV and oxygen permeability coefficient PeO2 for all obtained films.


Observing the water diffusivity values, we can conclude that the addition of NZ initially caused a reduction to water diffusivity i.e., a minimum value of 3.97 cm2/s to the content of 10% wt. Beyond that, the water vapor diffusivity starts to increase and, for NZ content 15% wt., its value became almost equal to the relevant of the initial raw material. In the case of TO@NZ hybrid nanostructure the minimum water diffusivity value observed for 5% wt. TO@NZ content and for 15% wt. content the water vapor diffusivity was higher than the relevant of the initial raw material. In general, 10% wt. NZ content in the polymer matrix exhibits a water vapor barrier almost equal to the relevant of 5% wt. TO@NZ content and lower enough compared to the relevant of the initial raw material. Beyond these concentrations, the extra addition of such nanostructured materials to the polymer matrix caused an increase to the water vapor diffusivity. Concerning the oxygen permeability, the minimum coefficient values compared to the relevant of the initial raw material were observed for 5% wt. NZ content and for 10 %wt. TO@NZ content. Increasing these concentrations, the oxygen permeability starts to increase. Considering Table 2 and according to the previous observations, we could say that the optimum NZ or TO@NZ additive concentration for the highest water vapor or oxygen barrier lies in the range of 5–10% wt.
